State Sen. Chris McDaniel has offered 15 rewards of $1,000 each to any person who can "provide evidence leading to the arrest and conviction of anyone involved in voter fraud" in the Republican primary for Senate in Mississippi.

On Thursday, his campaign announced the "challenge" in the latest episode in a circus of a Senate race. On June 24, incumbent Sen. Thad Cochran, R-Miss., defeated McDaniel in a primary runoff by 6,700 votes. But McDaniel has refused to concede, alleging Cochran's team paid for votes. McDaniel's team also charges some people voted in the Democratic primary earlier in the month and then voted for Cochran in the runoff, an illegal practice in Mississippi known as double voting.

The challenger's campaign is now asking supporters to donate $15 to the campaign to help fund the $15,000 in reward money.

It is not clear that the campaign will have to pay out any or all of that money: getting someone convicted for voter fraud is a high bar to clear.

"The most important issue here is maintaining the integrity of the electoral process here in Mississippi," McDaniel said in a statement. "These allegations of criminal behavior on behalf of the Cochran are troubling, and any evidence of fraud will be turned over to the authorities to be investigated."

A McDaniel spokesman said the “Election Integrity Challenge and Voter Fraud Reward” had been cleared with the campaign's lawyers. The contest and challenge may have the effect of padding McDaniel’s fledgling legal defense fund, established earlier this week. The fund will also pay for any reward recognized by the campaign.

On Wednesday, a conservative group took up McDaniel's cause and filed a lawsuit against the Mississippi Republican Party and the Secretary of State, alleging they had been denied access to election records in their pursuit of illegally cast votes.

The Cochran campaign's response?

"Put up or shut up," said Cochran campaign adviser Austin Barbour on a conference call Wednesday. The call devolved into chaos shortly thereafter, when someone who sounded like a McDaniel supporter interrupted with racially charged comments.

Eliza Newlin Carney contributed to this report. The race is rated Safe Republican by the Rothenberg Political Report/Roll Call.